1. Field of the Invention
The invention relates to fluid flotation sleep systems, commonly known as waterbeds, and in particular to a method of manufacturing water containers utilized therein and the product produced thereby.
2. Description of the Prior Art
Conventional waterbed construction has relied on the use of water mattresses which are basically unitary liquid-containing bags, cut and sealed in the basic shape that the mattress is to assume. The mattresses are ordinarily held in place by a rigid frame, and the rough shape of the mattress conforms by virtue of the fluidity of the water contained therein to the usually rather distortable restrictions of the construction of the mattress itself and to the confines of the frame. Samples of this type of construction are shown in U.S. Pat. Nos. 3,753,819 of Mollura and 3,753,823 of Kuss. The disadvantages of this type of construction are well known: the mattress is extremely awkward and heavy when filled; it is prone to develop leaks; there is no easy stepwise procedure for filling; and considerable undesirable wave motion and general instability result in use. Furthermore, the requirement for a rigid support surrounding the flexible mattress poses a hazard unless the support is sufficiently well padded to shield against inadvertent collisions.
An improvement to this traditional construction is disclosed in U.S. Pat. No. 4,221,013 of Angel M. Echevarria, one of the inventors herein. The patent discloses a mattress which comprises a foam box filled with a series of elongated water containers, each container containing water or other similar liquid such that the containers fill the entire cavity of the foam box. This results in a more adaptable design in which the compartments can be filled separately and to any level desired to increase the user's comfort, and in which any leaks incurred can be limited to each separate elongated water container.
Although the detailed process for making the water containers was not disclosed in that prior patent, a standard calendaring process was utilized. In particular, individual sheets of plastic were lapped with the overlap thereafter being sealed. The length of the seam, however, extended over the entire length of each water container. Although the separate water containers disclosed in that patent performed satisfactorily, the relatively long seam length is somewhat difficult to seal and leakage may occur after extended use. What is desired therefore is an improved process for constructing the water containers which would result in a much shorter seam segment and thus provide greater stability. Although a process for fabricating inflatable tubular members using an extrusion process for use in an air mattress is disclosed in the Francis U.S. Pat. No. 3,914,811, the process is not feasible for use in waterbed construction.